Electron flow device



Oct. 2, 1951 GQSLING 2,569,665

ELECTRON FLOW DEVICE Filed Nov. 18, 1949 a 32 in H h h M U 24fine/2202m- (Lsepk 5605/2659 Patented Oct. 2, 1951 ELECTRON FLOW DEVICEJoseph B. Gosling, Milwaukee, Wis., assignor to General ElectricCompany, a corporation of New York Application November 18, 1949, SerialNo. 128,163

6 Claims. 1

The present invention relates in general to electronics, and has moreparticular reference to electron fiow devices, especially electronicrectifiers, the same comprising improvements and betterments in devicesof the sort illustrated and described in United States Letters PatentNo. 2,332,428, of October 19, 1943.

An important object of the invention is to provide a new and improvedelectron flow device, comprising an envelope and embodying novelelectrode construction and arrangement allowing simplifications in theconstruction of the device, including its envelope, and having improvedperformance and operating characteristics, and at the same timeproviding a device of small, compact size.

Another important object is to provide a device of the charactermentioned having a metal cup adapted to serve both as the anode of thedevice and as a portion of the enclosing envelope; a further objectbeing to provide means for sealing the metal anode cup directly to glassenvelope portions.

Another important object of the invention is to provide a device of thecharacter mentioned having a corrugated envelope portion of glass, witha cup-shaped metal dome, forming a metal envelope portion hermeticallysealed to the corrugated glass envelope portion at an end thereof, and acathode structure supported on the remote end of said glass envelopeportion in position in said envelope to present an electron emittingelement of said cathode in operative position within said metal dome.

Another important object is to provide an improved, low cost structurethrough simplification of anode fabrication, including elimination ofmuch of the glass envelope portions, the struc- .ture allowing for theshortening of necessary exhaust schedules in conditioning the device foroperation, after fabrication thereof, said improved structure resultingin the elimination of dirt catching crevices at the anode end of thedevice.

.Another important object is to provide a device of the .charactermentioned having improved structural features providing for rapid heatdissipation from the anode to circumambient fluid in which the devicemay be disposed when in operation, thereby improving the maximum powerrating at which the device may safely be operated.

Another important object is to provide an improved structural design forelectron flow devices whereby devices embodying the new design may byallowing for the external support, as by chuck-' ing, of the anodeduring the assembly of the anode and'cathode structures and theattachment thereof on the glass portions of the envelope; a furtherobject being to provide an improved design eliminating the heretoforeconventional re-entrant anode seal envelope portion.

Another important object is to provide a device of the class describedfor operation as a fluid immersed unit for cooling purposes, and adaptedfor operation at exceedingly low temperature.

The foregoing and numerous other important objects, advantages, andinherent functions of the invention will become apparent as the same ismore fully understood from the following description, which, taken inconnection with the accompanying drawings, discloses a preferredembodiment of the invention.

Referring to the drawings:

Fig. l is a perspective view of an electronic rectifier embodying thepresent invention; and

Fig. 2 is a sectional view taken longitudinally through the device shownin Fig. 1.

To illustrate the invention, the drawings show an electronic device inthe form of a rectifier II, comprising a sealed envelope I2 of suitablematerial, an anode I3, and a cathode I 4.

The anode I3 comprises a hollow metal shell I5 of preferably cylindricalconfiguration, closed at one end to form a preferably hemispherical domeI6. Spaced behind its open end IS, the shell I5 is preferably formedwith a shoulder II, providing an external seat upon which a sealingskirt I8, preferably of sheet metal, may be snugly seated and sealed, asby welding or brazing with copper, as indicated at I9, circumferentiallyof the shell.

The sealing skirt I8 preferably comprises metal adapted readily to sealwith glass, and forms a sealing rim 20 outwardly of, concentric withrespect to, and preferably offset rearwardly of the open end I 6 of theshell I5. The skirt I8, and preferably also the shell I5, may be dieformed in a. suitable press and preferably comprise nickel-cobalt steel.

The envelope I2 comprises a glass member 2| of material adapted readilyto seal with the rim 26 of the metal skirt. The envelope portion l2preferably has a medial corrugated portion 22 and an open end comprisinga rim 23, sized to form a glass-metal seal with the rim 20 of thesealing skirt i8, whereby the anode shell may be sealingly integratedwith the glass envelope portion l2 and form one end of the envelope,with the open end iii of the shell projecting within the open end of theglass envelope portion, beyond the glass-metal seal, to thereby shieldthe seal against bombardment of electrons emitted by the cathode l4. Theinwardly extending bends 22 of the corrugations may have thicker wallsection than the remaining portions of the corrugations. These inwardlyextending bends are exposed to electronic bombardment to a greaterextent than are the outwardly extendin portions of the corrugations. Asa consequence, the greater thickness of the portions 22 aifordsdesirable dielectric strength at the zones of maximumelectrostaticstress.

The dome remote end of the envelope comprises a glass disk 24, formedwith a pair of spaced openings 25 in which cathode support stems 26 maybe assembled and sealed, as by means of cup-shaped sealing elements 21of metal adapted to seal readily with glass. These elements 21 maycomprise cup-shaped members sealed on the stems 26 outwardly of theenvelope to provide annular sealing rims adapted to form glass-metalseals with the glass material of the end wall 24 around the openings 25.The disk 24, stems 26, and the hereinafter more fully described cathodestructure l4 may be constructed as an assembly unit and then mounted inthe envelope by sealing the edges of the disk 24 to the dome remote endedges of the glass envelope portion 2|, as at 24', whereby the disk 24becomes an integral end closure wall of the en'- velope.

The stems 26 have portions 28 extending outwardly of the envelope forconnecting the cathode with an external power source, the cathodestructure l4 being supported on the stems 26 within the envelope. Saidcathode structure preferably comprises a pair of mounting stems 29 and29', each mounted on and electrically connected with a corresponding oneof the support stems 26. These mounting stems 29, 29', extend from thestems 26 within the envelope and into the anode shell IS, the stem 29preferably extending coaxially within the envelope and having sealedenclosing the stem connected ends of the members 29. 29', and forming ashield for protecting the same and the glass-metal seals of the stems 26against stray electron bombardment. To this end, the shell 30 may besealed on and electrically connected with the stem 29, as by welding itto a metal support sleeve 3| on the member 29. The member 39 maycomprise nickel or steel. The support stem 29' may be disposed inparallel spaced relationship with respect to the stem 29, and may extendthrough a suitable opening formed in the skirt 39, said member 29' beinginsulated from said skirt, as by means of a suitable insulating sleeve32. The upper end 33 of the stem 29' is bent and disposed in coaxialspaced relationship with respect to the upper end of the stem 29.

The cathode structure preferably comprises an electron emitting filament34 supported on the stems 29, 29', in position coaxially within theanode shell. To this end, the opposite ends of the filament 34 areelectrically connected, respective- 4 1y, with the spaced apart facingends of the stems 29, 29'. The portions of the stem 29' adjacent itsfilament connected end 33 are also preferably formed as a loop or loops35 about the electron emitting filament 34.

In order to insure against damage or destruction of the emission element34 as the result of inverse electrical discharge or flash-over from theanode to the emission element, flash arresting means maybe provided inthe form of a sheet metal disk 36, preferably comprising nickel, mountedon and electrically connected with the stem 29, as by welding it to ametal mounting collar 31 on the stem 29. The stem 29' may extend in anopening formed in the disk, outwardly of the collar 31, and the stem 29'may be insulated from the disk, as by means of an insulating collar 38;In order to improve its function, the peripheral edges of the disk maybe curled to semi-circular sectional configuration, to form a flashreceiving edge head 39 at the peripheral edge of the disk.

It should be understood, of course, that an electron flow device of thecharacter here considered functions as the result of flow of electronsemitted by the cathode element, which travel to and impinge upon theanode. When the device comprises a rectifier, the stream of electronspassing between the cathode and anode form a conduction path, alongwhich electrical current may flow in one direction only, so that suchuni-directional flow phenomena may be utilized for the purpose ofrectifying or converting alternating or fluctuating electrical energy toproduce uni-directional electrical power.

For efficient operation, the atmosphere within the envelope should bemaintained at low pressures of the order of 0.02 micron of mercury, andthe maintenance of low pressure conditions is of particular importance,since the operation of an electron flow device will result in theionization of any gas particles within the envelope and with which anelectron may collide during its travel between cathode and anode. Such acollision r results in the production of a positively charged ion, whichmay impinge upon the cathode element and dislodge therefrom a particleof its constituent material. In order, therefore, to preserve theemission element for long service life, among other things, it isdesirable to eliminate, as far as possible, all gaseous matter fromwithin the envelope. To this end, the envelope is thoroughly evacuatedas a part of the manufacture of the device, evacuation beingaccomplished after the constituent parts of the device have beenassembled and sealed in the envelope. During the evacuation of theenvelope, the device and all of its operating parts are strongly heatedin order to remove all impurities, including such gases as may beoccluded in the anode, cathode, and envelope walls.

The end wall 24 of the glass envelope portion may be pre-formed with acentral opening 40.for connection, as by means of a suitable glass tube,with an exhaust pump, in order that the device after assembly may beconditioned for operation by procedures including the evacuation of thesealed envelope. ,The envelope may be finally sealed at the conclusionof the conditioning process, in evacuated condition, by sealing oif theglass exhaust pump connection to form an integral sealing bead 4| at theopening 40, whereupon the device will be ready for service.

The device may be energized for operation by connecting the stem ends 28with a suitable source of cathode energizing power to promote electronflow from the emitter 34. The anode dome may be provided with a terminalstud 42 and clamp nut 43, forming means for electrically connecting thesame with a suitable conductor forming a part of a rectifying circuit,which may also be connected with one of the stem ends 28.

It will be seen from the foregoing that the device of the presentinvention represents substantial simplification as compared with devicesof the sort heretofore provided, as exemplified in United States LettersPatent No. 2,332,428. Not only have the expensive and relativelydiflicultly scalable re-entrant end portions of the glass envelope beeneliminated, thereby greatly simplifying the glass-metal envelope sealingoperations, but the over-all length of the device required for anyselected power rating has been very substantially diminished, to therebyreduce the overall space required for apparatus comprising severalrectifier devices forming a rectifying system. Rectifying systems,embodying rectifiers made in accordance with the teachings of thepresent invention, may thus be housed in substantially smaller casingsthan heretofore required for systems of equivalent power ratingcomprising units of the sort heretofore available. 1

Devices embodying the present invention, moreover, can be manufacturedat cost substantially lower than has heretofore-been possible, due tothe simplification of the anode itself, the elimination of much envelopeglass, and the arrangement of the glass-metal seal at 20 in anexternally accessible position, thereby greatly facilitating the sealingoperation, a further advantage residing in simplification of the sealingskirt l8 and its attachment on the anode element by circumferentialwelding or brazing.

The structure and arrangement of the present device also allows greateraccuracy and uniformity in the finished device, since the anode elementmay be positively supported, as in a suitable chuck, and held in exactposition with respect to the cathode structure during assembly andsealing of the anode element with the glass envelope portions, therebyassuring exact alinement of the filament 34 within the anode, in theflnished structure. This circumstance allows for the production ofdevices embodying the present invention on semi-automatic machines,thereby reducing production costs, the elimination of reentrant envelopeseal portions contributing to this desirable result.

Electron flow devices of the sort herein disclosed are commonly operatedin position immersed in insulating and cooling fluid, such as oil, towhich heat, generated as a result of the operation of the device, isdissipated. Devices embodying the structure of the present inventionprovide immeasurably better heat transference to the circumambientcooling fluid. As a consequence, the devices of the present inventionare adapted to operate at relatively low temperature as compared withcomparable devices of the sort heretofore known. Consequently, devicesenibodying the present invention may be given higher current ratings,and may thus safely perform substantially more work than comparabledevices of equivalent physical size heretofore available.

newsmall devices of the present invention operate at very much loweroil-metal interface temperature, because of the substantially greaterheat dissipating area of the anode in contact with the circumambientcooling fluid. Where the operating temperature of the anode in devicesheretofore available has been of the order of 200 C., theoperating'anode temperature in devices embodying the present inventionis of the order of 0., thereby minimizing the possibility ofdeterioration of the circumambient oil in which the devices are immersedfor operation.

It is thought that the invention and its numerous attendant advantageswill be fully understood from the foregoing descriptions, and it isobvious that numerous changes may be made in the form, construction andarrangement of the several parts without departing from the spirit or'scope of the invention, or sacrificing any of its attendant advantages,the form herein disclosed being a preferred embodiment for the purposeof illustrating the invention.

The invention is hereby claimed as follows:

1. An electron flow device comprising a sealed envelope embodying aglass envelope portion and a. metal shell sealed in end-to-endrelationship to form the opposite end portions of the envelope, saidglass portion and shell having matching seal rims forming acircumferential glass-metal seal medially of the opposite ends of saidenvelope, said glass portion being formed with circumferentialcorrugations between the ends thereof and tapering inwardly from itsshell sealed end toward the opposite end thereof, and a cathodestructure mounted within said envelope on said glass portion andsupporting an electron emitting element within said metal shell toconstitute the same as an anode adapted to dissipate heat therefromdirectly outwardly of said envelope.

2. An electron flow device comprising a sealed envelope embodying aglass envelope portion and a metal shell sealed in end-to-endrelationship to form the opposite, end portions of the envelope, saidglass portion and shell having matching seal rims forming acircumferential glassmetal seal medially of the opposite ends of saidenvelope, said glass portion being formed, between the ends thereof,with circumferential corrugations comprising alternate inwardly andoutwardly extending bends, said inwardly extending bends having greatersectional thickness than said outwardly extending bends, and a cathodestructure mounted within said envelope on said glass portion andsupporting an-electron emitting element within said metal shell toconstitute the same as an anode adapted to dissipate heat therefromdirectly outwardly of said envelope.

-3. An electron fiow device comprising a sealed envelope embodying aglass envelope portion and a metal shell sealed in end-to-endrelationship to form the opposite end portions of the envelope, saidglass portion and shell having matching seal rims forming acircumferential glassmetal seal medially of the opposite ends of saidenvelope, said glass portion being formed, be

said outwardly extending bends, said glass por-' tion tapering inwardlyfrom its shell connected end toward the remote end thereof, and acathode structure mounted within. said envelope on said glass portion atsaid shell remote end thereof, and supporting an electron emittingelement within said metal shell to constitute the same as an anodeadapted to dissipate heat therefrom directly outwardly of said envelope.

4. An electron flow device comprising a sealed envelope embodying a pairof cup-shaped envelope portions, respectively formed of glass and ofmetal, and having open ends circumferentially sealed together to form acomposite envelope of glass at one end and of metal at the other, and acathode structure mounted within said envelopgon the bottom of the glassmember in position supporting an electron emitting element within themetal member to constitute the same an an anode, said glass memberhaving side walls extending between the opposite ends thereof and formedwith circumferential corrugations com- 1 from said sealed end, said sidewalls being formed with circumferential corrugations embodying alternateinwardly and outwardly extending bends, said inwardly extending bendshaving greater sectional thickness than the remaining portions of saidside walls, and a cathode structure mounted on said bottom wall andhaving portions extending within said metal shell, said cathodestructure including an electron emitting element supported within andcentered upon the longitudinal axis of said metal shell, whereby toconstitute the same as the anode of said rectifier.

6. An electronic rectifier comprising a sealed envelope embodying aglass portion and a metal shell sealed in end-to-end relationship, saidglass portion and shell having matching seal rims forming acircumferential glass-metal seal medially of the'opposite ends of saidenvelope, said glass portion being formed with circumferentialcorrugations between the ends thereof and tapering inwardly from itsshell-sealed end toward the opposite end thereof, and a cathodestructure mounted within said envelope on said glass portion andsupporting an electron emitting element within said metal shell wherebyto constitute the same as an anode adapted to dissipate heat therefromdirectly outwardly of said envelope.

JOSEPH B. GOSLING.

' REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,933,329 Hull Oct. 31, 19332,385,435 Werner et a1 Sept. 25, 1945 Atlee et al July 26, 1949

